On June 30, 2006, at 1645 eastern daylight time, a Mooney M20M, N2168F registered to Buy Air LLC, operating as a 14 CFR Part 91 personal flight, went off the end of the runway at Mountain Air Airport, Burnsville, North Carolina. Visual meteorological conditions prevailed and no flight plan was filed. The airplane received substantial damage. The private pilot and three passengers reported no injuries. The flight originated from Alma, Georgia, on June 30, 2006, at 1500. The pilot stated he departed from Naples, Florida, with an enroute stop in Alma, Georgia, for fuel. Upon arrival in the Burnsville area, the pilot obtained the Asheville, North Carolina, surface winds. The winds were being reported as 340-degrees at 6 knots. The pilot contacted personnel on the ground at Mountain Air Airport over the UNICOM radio frequency and followed another airplane that was in front of his for landing. The pilot made a low pass down the runway and surveyed the landing area even though he had landed at the airport before. Upon completion of the low pass the pilot remained in right closed traffic. The pilot stated he completed the before landing checklist, lowered the landing gear, extended the flaps and activated the speed brakes. The pilot turned on final approach and extended the flaps to the full down position. When the airplane was over the landing threshold the pilot decreased the throttle. The airplane began to float, touched down on the runway, bounced and porpoised 3 times. The pilot stated the airplane must have encountered a tailwind. Once the airplane was on the ground on the landing roll out he began applying brakes. The airplane was approaching the end of the runway and the pilot locked the brakes. The airplane began to skid, went off the end of the runway, through the runway overrun, and down an embankment before it came to a complete stop. The pilot and three passengers exited the airplane. The pilot stated he did not encounter any mechanical problems with the airplane before the accident. The nearest weather reporting facility to the accident is Asheville Regional Airport, Asheville, North Carolina, located 27 nautical miles south of Mountain Air Airport. The 1654 surface weather information revealed the winds were 320-degrees at 6 knots.